The AR-21 was developed in the years after the arrival of the SDF-1, to serve the new United Earth
Government in the capacity of a replacement for the multitude of
5.56mm NATO rifles. The AR-21 was often overshadowed in development by
innovative bullpup designs, but was found to be the most accurate,
rugged, and light by the appropriations board. The AR-21's most
interesting features include a magazine that lies flush with the
trigger grip, easing fire while prone. To accommodate this, the
ammunition in the magazine points upward, rather than forward,
requiring a unique rotating feed mechanism. Though some parties
considered the AR-21 overcomplex, it was a popular rifle, and served
with distinction until replaced by the Wolverine in the 2020s.